public sealed class ProjectManagementPackage : DocumentPackage

Public NotInheritable Class ProjectManagementPackage
	Inherits DocumentPackage

public ref class ProjectManagementPackage sealed : public DocumentPackage

[<SealedAttribute>]
type ProjectManagementPackage =  
    class
        inherit DocumentPackage
    end

using (Metadata metadata = new Metadata(Constants.InputMpp))
{
    var root = metadata.GetRootPackage<ProjectManagementRootPackage>();

    root.DocumentProperties.Author = "test author";
    root.DocumentProperties.CreationDate = DateTime.Now;
    root.DocumentProperties.Company = "GroupDocs";
    root.DocumentProperties.Comments = "test comment";
    root.DocumentProperties.Keywords = "metadata, built-in, update";

    // ... 

    metadata.Save(Constants.OutputMpp);
}